Reciprocating electromagnetic actu-



July 28, 1964 R. B. GELENIUS 3,142,788 RECIPROCATING ELECTROMAGNETIC ACTUATOR WITH FLUX SHUNTING MEMBER Filed Feb. 10, 1961 Pulsar/71g 0mm Current Fig. I

INVENTQR. Rob en E. Galen/us Fig. 2 BY (LR W His Attorney United States Patent This invention relates to an electromagnetic actuator that is operable to alternately transfer a load between two positions when a pulsating direct current is applied to the input terminals of the actuator.

One of the objects of this invention is to provide a reciprocating electromagnetic actuator that includes a coil winding and a shiftable plunger together with a magnetic sleeve slidable on the plunger for controlling the flux I applied to different parts of the plunger and therefore the magnetic force applied to the plunger.

Another object of this invention is to provide a reciprocating electromagnetic actuator that includes a coil winding, pole pieces and a plunger that is shifted by magnetic forces derived from the coil winding and pole pieces and further wherein a sleeve is provided that is shiftable relative to the plunger to control the magnetic force applied to the plunger, there being spring means provided for shifting the sleeve once the plunger has shifted.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown.

In the drawings:

FIGURE 1 is a sectional view of an electromagnetic actuator made in accordance with this invention.

FIGURE 2 is a sectional view taken along line 22 of FIGURE 1.

Referring now to the drawings, the electromagnetic actuator comprises a housing or shell 10 which is formed of asuitable magnetic material such as steel. The shell or housing 10 is secured to and supports pole pieces 12 and 14 which are likewise formed of magnetic material. The pole pieces 12 and 14 support a sleeve 16 which is formed of a suitable non-magnetic material. The sleeve 16 may be formed of a plastic material as shown or may be formed of some metal non-magnetic material such as brass. The sleeve 16 carriesa coil winding 18 which terminates in lead-in conductors 20 and 22.

The shiftable part of the electromagnetic actuator includes a plunger which is generally designated by reference numeral 24. This plunger has conical ends 26 and 28 which are the same shape as the conical recesses 30 and 32 formed in the pole pieces 12 and 14. The plunger 24 in its midsection is circular in cross section and has a radially extending slot 34 and axially extending chambers 36 and 38. The axially extending chambers 36 and 38 are circular in cross-section as is apparent from an inspection of FIGURE 2.

The plunger 24 carries an annular sleeve 40 which is formed of magnetic material such as steel. This. sleeve is positioned on the circular portion of the plunger and it is seen that a pin 42 is fixed to the sleeve which rides in the slot 34. A pair of springs 44 and 46 engage ICC opposite sides of the pin 42 and also engage the end walls of the chambers 36 and 38. It can be seen that this sleeve 40 is positioned to engage the annular walls 47 and 48 of the pole pieces 14 and 12 as the sleeve is shifted.

The plunger 24 is connected with a rod 50 which is, in turn, connected to a load 52 to be shifted between alternate positions. The load 52 slides in a support member 54 and there is friction between the load 52 and the support member 54. It can be seen that the support member 54 will limit movement of the load 52between the two positions and in the position illustrated in FIG- URE l, the load 52 cannot move any further leftwardly.

It is seen that the lead wires 20 and 22 which are connected with the opposite ends of the coil winding 18 are connected respectively with a source of pulsating direct current 56 and a manually operable switch 58. The source of pulsating direct current may be of any well known type that will produce a series of current pulses having a predetermined time interval between each pulse. As one example of such a source, a battery could be connected in series with a switch that opens and closes at a periodic frequency. It will be appreciated that when the manually operable switch 58 is closed, the source of pulsating direct current 56 is connected with the coil winding 18 so that it will be energized at a predetermined rate.

In describing the operation of this electromagnetic actuator, let it be assumed that the parts of the actuator are in the position illustrated in FIGURE 1. If the switch 58 is now closed, the coil winding 18 is energized with a pulse of direct current. This pulse of direct current will cause a flux to be produced which will pass through the pole piece 12, across the air gap to the right end 26 of the plunger 24 and thence through sleeve 40 to the pole piece 14 where the magnetic circuit is returned via the shell 10. A greater portion of the total flux will pass between the conical surface of pole piece 12 and the end 26 of the plunger 24 than is transferred between the annular section 48 of pole piece 12 and the sleeve 40. This is true because the reluctance between the pole piece 12 and the end 26 of the plunger is less than the reluctance of pole piece 12 and the sleeve 40. The flux path from the plunger 24 to the pole piece 14 can be either through the sleeve 40 or through the air gap between the end 28 of the plunger and the conical wall 32 of pole piece 14. It is pointed out here that the load 52 cannot shift leftwardly a distance suflicient to cause the end 28 of the plunger to contact the pole piece 14 and this air. gap between the plunger and pole piece will therefore always exist. Since the sleeve 40 is in direct contact with the annular section 47 of pole piece 14, a majority of the flux will pass directly to the pole piece 14 through the sleeve 40 and will be shunted away from the air gap between the end 28 of the plunger and the pole piece 14.

The unbalance of flux on the ends of the plunger 24 will produce a resultant force which moves the plunger 24 and the load 52 rightwardly. In moving to the. right, the end 26 of plunger 24 cannot contact the pole piece 12 since the support 54 limits the movement of the plunger 24 to maintain the same air gap that previously existed between the end 28 and pole piece 14. During this rightward movement of the plunger 24, the sleeve 40 will remain stationary since the magnetic forces are greater to hold it against pole piece 14 than to cause it toshift into engagement with pole piece 12. With plunger 24 shifted rightwardly and sleeve 40 stationary, it can be seen that the spring 46 will be compressed. As the current pulse from the source 56 now declines to zero, the coil winding 18 is no longer energized so that there is no longer a magnetic force holding the sleeve 40 against pole piece 14. The plunger 24 in this set of circumstances will remain stationary due to the friction between the load 52 and the support 54 while the sleeve 40 will be shifted rightwardly into engagement with the annular portion 48 of pole piece 12 by the spring 46.

The next time that a current pulse is supplied to coil winding 18, the cycle of events reverses so that plunger 24 and the sleeve 40 are shifted back into the FIGURE 1 position. This shifting back and forth of the plunger 24 will occur as long as the switch 58 is closed and will be at a rate determined by the frequency of the pulsating direct current source 56.

While the embodiments of the present invention as herein disclosed, constitute a preferred form, it is to be understood that other forms might be adopted.

. What is claimed is as follows:

1. A reciprocable electromagnetic actuator comprising, first and second pole pieces, a coil winding magnetically coupled with said pole pieces, a plunger aligned with and reciprocable between said pole pieces, means preventing engagement between said plunger and pole pieces when the plunger is shifted in either direction, a sleeve member formed of magnetic material slidable on said plunger and slidable between said pole pieces, said sleeve member being engageable with one of said pole pieces when the sleeve member is shifted in either direction and means for causing said sleeve member to shift from one pole piece to the other when said coil winding is inactive and in response to movement of said plunger from one position to another.

2. A reciprocable electromagnetic actuator comprising, first and second spaced polepieces, a coil winding magnetically coupled with said pole pieces, a plunger reciprocable between said pole pieces, means limiting movement of said plunger so that said plunger cannot engage the pole pieces in either direction of movement, a sleeve member formed of'magnetic material slidably supported on said plunger, a slot formed in said plunger, pin means connected with said sleeve member and passing through said slot, said slot being arranged to permit slidable movement of said sleeve with respect to said plunger, and first and second springs interposed between portions of said plunger and said pin means, said springs causing said sleeve member to follow movement of said plunger in either direction of its movement when said control winding is inactive. V

3. A reciprocable electromagnetic actuator comprising, an armature formed of magnetic material shiftable between two actuating positions, pole piece means providing air gaps between two diiferent portions of said armature and said pole piece means, said air gaps varying as said armature is shifted, means preventing engagement between saidarmature and pole piece means in either direction of movement of said armature to maintain predetermined air gaps at each actuated position of said armature, a coil winding magnetically coupled with said pole piece means, a flux shunting member formed of magnetic material magnetically coupled with said armature and shiftable relative thereto into engagement with one or the other of said pole piece means depending upon the direction of movement of said armature, and means interposed between said armature and said member for causing saidflux shunting member to shift from a position engaging one pole piece'means to a position engaging said other pole piece means when said coil winding is inactive and in response to shiftable movement of said armature.

4. An electromagnetic actuator comprising, magnetic 4 means providing first and second magnetic poles, a part formed of magnetic material shiftable between two actuated positions by magnetic attraction of said magnetic poles, means preventing engagement between said part and said magnetic poles when said part is in either of its actuated positions whereby :air gaps are always maintained between said part and said magnetic poles in either actuated position of said part, said air gaps varying as said part is shifted, a shiftable flux shunting member operable to provide a magnetic circuit between said part and one of said poles when said part-is shifted to one of its actuated positions to thereby shunt flux away from the magnetic path existing between said part and said one pole, said shiftable flux shunting member being shiftable to another position to provide a magnetic circuit between said part and the other of said poles to thereby shunt flux away from the magnetic path existing between said part and said other pole and means interposed between said part and said flux shunting member for causing said flux shunting member to follow the movement of said part when said magnetic poles are not capable of attracting said flux shunting member.

5. An electromagnetic actuator comprising, a source of magnetic flux, first and second magnetic poles magneti cally coupled with said source of magnetic flux, an armature member formed of magnetic material shiftable be- 1 tween first and second actuated positions by magnetic attraction of said poles and forming a flux path for flux passing between said poles, and a shiftable flux shunting member formed of magnetic material operable in different shifted positions to shunt flux respectively away from different flux paths existing between said armature member and said poles to thereby unbalance the flux passing between different parts of said armature member and said poles and means for causing said flux shunting member to follow movement of said armature when said poles V are not capable of attracting said flux shunting member.

6. A reciprocable electromagnetic actuator comprising, a source of variable magnetic flux, first and second pole pieces located in a magnetic circuit with said source of flux and axially spaced from each other, an armature shiftable between said pole pieces, means limiting movement of said armature in either direction such that a predetermined air gap is always maintained between an end of the armature and one of said pole pieces when said armature is moved to the limit of its movement, a

shiftable flux shunting member, said flux shunting member being shiftable between positions where it engages said pole pieces, and means for causing said flux shunting member to shift in the same direction as said armature has been shifted when said source ofmagnetic flux is reduced to a point where it is incapable of attracting said ture. has moved to the limit of its movement, a shiftable flux shunting member, said flux shunting member being shiftable between positions where it forms a path for shunting flux away from the path existing between said armature and one of said pole pieces, and means for causing said flux shunting member to shift in the same direction as said armature has been shifted when said single source of magnetic flux is reduced to a point that it no longer attracts said flux shunting member.

8. A reciprocable electromagnetic actuator comprising, a single source of magnetic flux, first and second pole pieces located in a magnetic circuit with a source of flux and axially spaced from each other, an armature shiftable between said pieces, said armature being operative to provide a magnetic circuit for flux flowing between said pole pieces, means limiting movement of said armature in either direction such that a predetermined air gap is always maintained between the armature and one of the pole pieces when said armature is moved to the limit of its movement, a shiftable flux shunting member, said flux 5 and the armature, and means for causing said flux shurit- 10 ing member to shift in the same direction as said armature has been shifted when said source of magnetic flux is reduced to a point where it no longer at-tracts said flux shunting member.

References Cited in the file of this patent UNITED STATES PATENTS 2,756,302 Baltuch July 24, 1956 2,885,606 Clements May 5, 1959 2,967,983 Danklefs Jan. 10, 1961 

5. AN ELECTROMAGNETIC ACTUATOR COMPRISING, A SOURCE OF MAGNETIC FLUX, FIRST AND SECOND MAGNETIC POLES MAGNETICALLY COUPLED WITH SAID SOURCE OF MAGNETIC FLUX, AN ARMATURE MEMBER FORMED OF MAGNETIC MATERIAL SHIFTABLE BETWEEN FIRST AND SECOND ACTUATED POSITIONS BY MAGNETIC ATTRACTION OF SAID POLES AND FORMING A FLUX PATH FOR FLUX PASSING BETWEEN SAID POLES, AND A SHIFTABLE FLUX SHUNTING MEMBER FORMED OF MAGNETIC MATERIAL OPERABLE IN DIFFERENT SHIFTED POSITIONS TO SHUNT FLUX RESPECTIVELY AWAY FROM DIFFERENT FLUX PATHS EXISTING BETWEEN SAID ARMATURE MEMBER AND SAID POLES TO THEREBY UNBALANCE THE FLUX PASSING BETWEEN DIFFERENT PARTS OF SAID ARMATURE MEMBER AND SAID POLES AND MEANS FOR CAUSING SAID FLUX SHUNTING MEMBER TO FOLLOW MOVEMENT OF SAID ARMATURE WHEN SAID POLES ARE NOT CAPABLE OF ATTRACTING SAID FLUX SHUNTING MEMBER. 